Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate Ligands
Two novel iminophenolate ligands with amidopropyl side chains (<b>HL2</b> and <b>HL3</b>) on the imine functionality have been synthesized in order to prepare dioxidomolybdenum(VI) complexes of the general structure [MoO<sub>2</sub><b>L<sub>2</sub&g...
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MDPI AG
2019-05-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/24/9/1814 |
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| author | Niklas Zwettler Madeleine A. Ehweiner Jörg A. Schachner Antoine Dupé Ferdinand Belaj Nadia C. Mösch-Zanetti |
| author_facet | Niklas Zwettler Madeleine A. Ehweiner Jörg A. Schachner Antoine Dupé Ferdinand Belaj Nadia C. Mösch-Zanetti |
| author_sort | Niklas Zwettler |
| collection | DOAJ |
| description | Two novel iminophenolate ligands with amidopropyl side chains (<b>HL2</b> and <b>HL3</b>) on the imine functionality have been synthesized in order to prepare dioxidomolybdenum(VI) complexes of the general structure [MoO<sub>2</sub><b>L<sub>2</sub></b>] featuring pendant internal hydrogen bond donors. For reasons of comparison, a previously published complex featuring <i>n</i>-butyl side chains (<b>L1</b>) was included in the investigation. Three complexes (<b>1</b>–<b>3</b>) obtained using these ligands (<b>HL1</b>–<b>HL3</b>) were able to activate dioxygen in an in situ approach: The intermediate molybdenum(IV) species [MoO(PMe<sub>3</sub>)<b>L<sub>2</sub></b>] is first generated by treatment with an excess of PMe<sub>3</sub>. Subsequent reaction with dioxygen leads to oxido peroxido complexes of the structure [MoO(O<sub>2</sub>)<b>L<sub>2</sub></b>]. For the complex employing the ligand with the <i>n</i>-butyl side chain, the isolation of the oxidomolybdenum(IV) phosphino complex [MoO(PMe<sub>3</sub>)(<b>L1</b>)<sub>2</sub>] (<b>4</b>) was successful, whereas the respective Mo(IV) species employing the ligands with the amidopropyl side chains were found to be not stable enough to be isolated. The three oxido peroxido complexes of the structure [MoO(O<sub>2</sub>)<b>L<sub>2</sub></b>] (<b>9</b>–<b>11</b>) were systematically compared to assess the influence of internal hydrogen bonds on the geometry as well as the catalytic activity in aerobic oxidation. All complexes were characterized by spectroscopic means. Furthermore, molecular structures were determined by single-crystal X-ray diffraction analyses of <b>HL3</b>, <b>1</b>–<b>3</b>, <b>9</b>–<b>11</b> together with three polynuclear products {[MoO(<b>L2</b>)<sub>2</sub>]<sub>2</sub>(µ-O)} (<b>7</b>), {[MoO(<b>L2</b>)]<sub>4</sub>(µ-O)<sub>6</sub>} (<b>8</b>) and [C<sub>9</sub>H<sub>13</sub>N<sub>2</sub>O]<sub>4</sub>[Mo<sub>8</sub>O<sub>26</sub>]·6OPMe<sub>3</sub> (<b>12</b>) which were obtained during the synthesis of reduced complexes of the type [MoO(PMe<sub>3</sub>)<b>L<sub>2</sub></b>] (<b>4</b>–<b>6</b>). |
| first_indexed | 2024-12-23T23:22:44Z |
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| language | English |
| last_indexed | 2024-12-23T23:22:44Z |
| publishDate | 2019-05-01 |
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| series | Molecules |
| spelling | doaj.art-f07471ebdcab4ee9ab619bc7f12d8cb12022-12-21T17:26:17ZengMDPI AGMolecules1420-30492019-05-01249181410.3390/molecules24091814molecules24091814Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate LigandsNiklas Zwettler0Madeleine A. Ehweiner1Jörg A. Schachner2Antoine Dupé3Ferdinand Belaj4Nadia C. Mösch-Zanetti5Institute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, AustriaInstitute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, AustriaInstitute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, AustriaInstitute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, AustriaInstitute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, AustriaInstitute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, AustriaTwo novel iminophenolate ligands with amidopropyl side chains (<b>HL2</b> and <b>HL3</b>) on the imine functionality have been synthesized in order to prepare dioxidomolybdenum(VI) complexes of the general structure [MoO<sub>2</sub><b>L<sub>2</sub></b>] featuring pendant internal hydrogen bond donors. For reasons of comparison, a previously published complex featuring <i>n</i>-butyl side chains (<b>L1</b>) was included in the investigation. Three complexes (<b>1</b>–<b>3</b>) obtained using these ligands (<b>HL1</b>–<b>HL3</b>) were able to activate dioxygen in an in situ approach: The intermediate molybdenum(IV) species [MoO(PMe<sub>3</sub>)<b>L<sub>2</sub></b>] is first generated by treatment with an excess of PMe<sub>3</sub>. Subsequent reaction with dioxygen leads to oxido peroxido complexes of the structure [MoO(O<sub>2</sub>)<b>L<sub>2</sub></b>]. For the complex employing the ligand with the <i>n</i>-butyl side chain, the isolation of the oxidomolybdenum(IV) phosphino complex [MoO(PMe<sub>3</sub>)(<b>L1</b>)<sub>2</sub>] (<b>4</b>) was successful, whereas the respective Mo(IV) species employing the ligands with the amidopropyl side chains were found to be not stable enough to be isolated. The three oxido peroxido complexes of the structure [MoO(O<sub>2</sub>)<b>L<sub>2</sub></b>] (<b>9</b>–<b>11</b>) were systematically compared to assess the influence of internal hydrogen bonds on the geometry as well as the catalytic activity in aerobic oxidation. All complexes were characterized by spectroscopic means. Furthermore, molecular structures were determined by single-crystal X-ray diffraction analyses of <b>HL3</b>, <b>1</b>–<b>3</b>, <b>9</b>–<b>11</b> together with three polynuclear products {[MoO(<b>L2</b>)<sub>2</sub>]<sub>2</sub>(µ-O)} (<b>7</b>), {[MoO(<b>L2</b>)]<sub>4</sub>(µ-O)<sub>6</sub>} (<b>8</b>) and [C<sub>9</sub>H<sub>13</sub>N<sub>2</sub>O]<sub>4</sub>[Mo<sub>8</sub>O<sub>26</sub>]·6OPMe<sub>3</sub> (<b>12</b>) which were obtained during the synthesis of reduced complexes of the type [MoO(PMe<sub>3</sub>)<b>L<sub>2</sub></b>] (<b>4</b>–<b>6</b>).https://www.mdpi.com/1420-3049/24/9/1814molybdenumiminophenolate ligandsdioxygen activationperoxido complexes |
| spellingShingle | Niklas Zwettler Madeleine A. Ehweiner Jörg A. Schachner Antoine Dupé Ferdinand Belaj Nadia C. Mösch-Zanetti Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate Ligands Molecules molybdenum iminophenolate ligands dioxygen activation peroxido complexes |
| title | Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate Ligands |
| title_full | Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate Ligands |
| title_fullStr | Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate Ligands |
| title_full_unstemmed | Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate Ligands |
| title_short | Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate Ligands |
| title_sort | dioxygen activation with molybdenum complexes bearing amide functionalized iminophenolate ligands |
| topic | molybdenum iminophenolate ligands dioxygen activation peroxido complexes |
| url | https://www.mdpi.com/1420-3049/24/9/1814 |
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